[fenceguy]

Im trying to form a cap for a fence that I have built with 4x4 posts 2x4 rails and 5/4 deckboard fence posts. The plan was to rip 1" cuts over and over until I have cleared out a one inch deep track 6.25" wide leaving 1 and 5/8" inches on either side of a 2x10. It takes a little over an hour to do one 16 footer and that doesn't include cleaning it up. Does anyone have any thoughts? I have 300' to go.

 

[DonkeyHody]

I think you're doing it the hard way. Rip some 1 and 5/8" strips and glue/screw them to the bottom side of your 2X10. It'll sit an inch higher, but who cares?

 

[Cherryville Chuck]

Sounds like Andy has a better idea. Possibly even better is to step Andy's strips back about 1/2" and then 1/4" in from the edges cut a groove with a table saw or circular saw about 1/4" deep. That will prevent water from rolling around the edge and getting into the strips Andy is suggesting, which will help prevent premature rotting. That's what I do when I make window sills.

 

[DaninVan]

What they said. With an air-nailer you'll be done by lunch tomorrow. I second Charles comment about the drip grove.
Mind you, if it's all pressure treated.
Rather than attach them to the 2x10" I just use PT 1x2 and brad nail them to the fence boards, tight up to the underside of the top cap. Just to be clear, I put mine on with the 3/4' edge on top, ie the 1 1/2" dimension is facing outwards.
Make sure you buy hot galv. airnails. 18ga is just fine...16ga if you have them.